Lesson Worksheet: Exterior Angles of a Triangle Mathematics • 8th Grade

In this worksheet, we will practice finding the measure of the exterior angle of a triangle and comparing between an exterior angle and its corresponding remote interior angles.


What is the sum of the measures of the exterior angles of a triangle?


Is π‘šβˆ π΄π·π‘Œ<, =, or >π‘šβˆ π΄πΆπ·?

  • A=
  • B<
  • C>


The figure shows some angles identified on triangle 𝐴𝐡𝐢.

Identify which angle is an exterior angle.

  • A𝑦
  • Bπ‘₯
  • C𝑧

Identify which angle is an interior angle.

  • A𝑧
  • Bπ‘₯
  • C𝑦


Is the measure of two right angles less than, equal to or greater than the sum of the interior angles of a triangle?

  • Aless than
  • Bgreater than
  • Cequal to


The figure shows the exterior angles of a given triangle. Find the sum of the exterior angles.


What is the measure of an exterior angle of an equilateral triangle?


Find π‘šβˆ πΆπ΄πΈ.


True or False: It is possible to draw a triangle on a plane with two obtuse angles.

  • ATrue
  • BFalse


In a triangle π‘‹π‘Œπ‘, if π‘‹π‘Œ=𝑋𝑍, what type of angle is the exterior angle at vertex 𝑍?

  • Aright
  • Breflex
  • Cacute
  • Dobtuse


Which of the following inequalities is correct?

  • Aπ‘šβˆ π‘‹π‘Œπ‘>π‘šβˆ π‘‹π‘Œπ‘†>π‘šβˆ π‘‹π‘π‘Œ
  • Bπ‘šβˆ π‘‹>π‘šβˆ π‘‹π‘π‘Œ>π‘šβˆ π‘‹π‘Œπ‘
  • Cπ‘šβˆ π‘‹π‘Œπ‘†>π‘šβˆ π‘‹π‘π‘Œ>π‘šβˆ π‘‹π‘Œπ‘
  • Dπ‘šβˆ π‘‹π‘π‘‡>π‘šβˆ π‘‹>π‘šβˆ π‘‹π‘π‘Œ
  • Eπ‘šβˆ π‘‹π‘π‘Œ>π‘šβˆ π‘‹π‘Œπ‘>π‘šβˆ π‘‹

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